There are many percutaneous medical devices that function to evacuate air or fluid from body cavities. Conventional catheters may be inserted using a guidewire and moved into the body to almost any desired location. Once located in position, the guidewire is typically removed. Other similar functioning percutaneous devices function to administer a substance, such as a drug, into the body cavity or into a vascular lumen. Most of these devices are elongated and tubular, sharing a common method of placement over or with the aid of the guidewire. A common method for placement of these devices employing a guidewire, is known as the “Seldinger technique.”
The Seldinger technique has revolutionized the practice of medicine by allowing procedures that were previously done with “open” surgical technique to be performed with “closed,” percutaneous technique. As is evident from the following description of the Seldinger technique, the “closed” percutaneous method results in an incision that is just large enough to pass the medical device via a needle initiated “tract” down to the desired, hollow cavity or “lumen.”
To perform the Seldinger technique, a hollow hypodermic needle of the necessary length and rigidity to reach the desired body cavity or lumen is passed through the skin surface until the distal tip of the needle is in the cavity or lumen. The needle is often of a much smaller diameter than the medical device that will subsequently be placed in order to minimize damage in the event the cavity or lumen is missed initially. The position of the distal tip of the needle is then verified by aspirating the appropriate body fluid or air into a syringe. In difficult to access cavities or lumens, fluoroscopic or other radiologic imaging can be utilized to guide and confirm placement. A flexible guidewire is then passed into the proximal hub of the needle, through the lumen of the needle and into the cavity or lumen. Control is maintained at the distal aspect, or exposed length of the guidewire. Next, the guidewire is held in position while the needle is withdrawn over the distal aspect of the guidewire and removed entirely from the distal end of the guidewire.
The elongated, tubular medical device, commonly known as a catheter or a drainage tube, can be too large and too pliable to easily pass over the guidewire, through the needle tract made in the skin and tissues, and into the desired body cavity or lumen. Often, a superficial dermatotomy, commonly referred to as a “skin-nick,” is then performed with a surgical scalpel blade immediately adjacent to the entry of the guidewire, to enlarge the entry site. A rigid dilator is often then passed over the guidewire to enlarge the deeper aspects of the tract and allow the subsequent medical device to pass smoothly over the guidewire into the desired cavity or lumen.
A well-made skin nick should contain the guidewire and should be large enough to admit the medical device. It should not be so large or so deep as to allow leakage of body fluids around the subsequently placed medical device, or to excessively compromise the function of the skin as a barrier to infection. If the nick is made away from the entry site of the wire or is not sufficiently deep, the dilator, and or the medical device, will not pass over the guidewire and through the skin and tissues easily. If excessive force is employed, the tip of the dilator, and or the medical device, can flare and bind at the skin surface.
In spite of the fact that a guidewire leads to the precise place where the skin nick is to be made, the dermatotomy is often performed with a traditional scalpel, employing only the visual guidance and the free hand of the operator. In urgent settings, with poorly positioned patients, in poorly lighted rooms, a precisely placed skin nick can require significant concentration at a time when there are other pressing issues with the patient.
Devices produced to minimize these safety and procedural difficulties, as encountered in performing dermatotomies in conjunction with percutaneous placements of guidewires or the like, include the type found in U.S. Pat. No. 7,341,596 to J. Scott Heppler, which is useful in minimizing the potential for inadvertent lacerations in the precise performance of skin-nicks, to which the present device further improves. The present invention addresses these needs and will be better understood by reference to the following detailed description taken in conjunction with the accompanying drawings.